Fluid pressure cycling system



June l2, 1951 .J. A. SENN FLUID PRESSURE CYCLING SYSTEM Filed Nov. 2,1945 June l2, 1951 J. A. sENN 2,556,603

FLUID PRESSURE CYCLING SYSTEM Filed Nov. 2. 1945 2 Sheets-Sheet 2Patented .une 1.2, 1951 UNITED STATES PATENT OFFICE FLUID PRESSURE`CYCLING SYSTEM Jurg A. Senn, Milwaukee, Wis.

Application November 2, 1945, Serial No. 626,342

This invention relates to cycling systems and particularly to devicesvofthis class which supply current to an electric heater in the incrementsnecessary to replace the heat dissipated by a body heated by suchheater. In supplying current to surface burner units of electric ranges,for example, it has been proposed to provide a temperature sensitive orfeeler element centrally of the burner coil and in contact with thebottom of the pan to feel the temperature thereof. The heat received bythe feeler unit is converted to fluid pressure acting upon a remotelylocated pressure diaphragm which serves to adjust the position of a pairof cooperating switch elements with respect to a switch-opening cyclingcam. A

single cycling cam may be arranged to actuate several sets of switchelements spaced there about, four for example, corresponding to thenumber of surface plates of the usual electric range. This grouping ofthe switch arms for the respective heater plates about the centralcycling cam is disadvantageous and difficult to attainy however, whereonly the customary long and relatively narrow range switch panel isavailable. n .g'An object of` this invention is to provide a cyclingsystem for electric heaters in which the cycling source is fluid-coupledto the switch cycledthereby and hence may be located remote from thelatter.

An additional object of the present invention is to provide a cyclingsystem for electric heating plates in which both the feeler element andthe cycling cam exert additive fluid pressure upon one or moreexpansible, switch-moving diav. Another object is to provide a cyclingsystem for electric heaters in whichthe feeler element, cycling sourceand switch-actuating diaphragm are connected by a common, liquid-filledconduit.

Another object is to provide a cycling system for electric heaters inwhich the feeler element and cycling source are fluid-coupled torespective switch-actuating diaphragms.

A further Objectis to provide a cycling system for electric' heaters inwhich the cycling switch movement results from the periodic electricheating of the fluid within a sealed diaphragm by a resistance meanslocated adjacent thereto.

Another object is to provide a switch for o cycling systems asdescribed-in which the zero adjustment is effected by shifting a portionof the switch lever engaged by the range cam thereby effecting aconsiderable simplification in Switch construction.y f

21 Claims. (Cl. 20G-83) A further object is to provide a switch forcycling systems as described characterized by ilexible, hinge-mountedswitch arms thus elimif nating lost motion, friction and misalignment ofparts.

Other objects and advantages of the invention will appear as thedescription thereof proceeds.

Reference is now made to the drawing wherein Fig. l is a verticalsectional view of one form of my invention and is taken on the line l-Iof Fig. 2;

Fig. 2 is a top View of the switch shown in Fig. l and is taken on theline 2-2 of Fig. 1; Fig. 3 is a modification of the construction of Fig.l and 'shows the replacement of the cycling cam l5 by an electricallyheated sealed diaphragm;

Fig. 4 is a vertical sectional view of a simplied form of fluid actuatedcycling switch according to the systems of Figs. l and 3 and taken onthe line 4 4 of Fig. 5; and

Fig. 5 is a top View of the switch of Fig. 4 with the cover 6'1 removed.

Fig. 6 is a vertical sectional View of the form of my invention shown inFig. l as modied by the construction shown in Fig. 3, taken on line E`Gof Fig. 7, and Fig. '7 is a sectional elevation taken on the line '1 1of Fig. 6.

Referring now to Fig. 1 there is indicated at I a switch housing havinga bottom` wall 2 through which extends a threaded nipple 3 held in placeby a nut 4 thereon. A flexible diaphragm assembly 5 including an upperelement 5a and a similar lower element 5b peripherally united thereto issecured to the top of the nipple 3 as by welding and is centrallyapertured as shown to receive liquid under pressure through the bore ofthe nipple. A follower spring 6 is secured by a screw 'l to a block 8which may be mounted on the housing in any suitable manner and carrieson its opposite end a contact block 9 for transmitting the pressure ofthe diaphragm element 5c to the switch mechanism properly describedhereinafter. The bore of nipple 3 is suitably united to a conduit l0which has a lateral portion Illa terminating in a constant volume heatdetector or feeler member I l which in range application is usuallyplaced at the center of the burner plate and in spaced, surroundedrelation- Aship with the latter.

Thus, as the temperature of the pan contacting thevfeeler member Il israised, the fluid therein will be forced through conduit l0 into thediaphragm 5 which is expanded thereby to move the block 9 upwardly.Another branch Ib of the conduit I connects to a bored nipple I2 servingas a mount for a variable volume liquid reservoir such as a centrallyapertured, flexible diaphragm I3 which is adapted to be filled with theliquid from conduit Ib. A contact button I4 is mounted centrally of theouter element of diaphragm I3 and is adapted to be laterally displacedby the throw of an eccentric cam I5 mounted on a shaft I6 which isprefer ably driven at a uniform speed by a suitable motor (not shown) toperiodically force the liquid out of diaphragm I3 and into diaphragm 5to thereby move the block 9 upwardly against the influence of follow-upspring 5.

A pin I'I extends transversely of the switch housing I and through theside walls I8 thereof and constitutes a fulcrum for an angular leverblock I5 preferably of insulating material and having an arm I9a adaptedto contact an adjustable stop preferably in the form of a screw as 25threaded through a block 2i fixed to the housing I by a screw 22. Leverblock I9 serves as a rock.- ing support for a pair of spaced, parallelswitch arms 23 secured to the block by screws 23a and having contacts 24on the ends thereof adapted to be bridged by a bar contact 25 secured byrivet 25a to the end of a generally triangular lever 2S having parallelside walls 26a through which extends the shaft I1 as a pivot.

A generally triangular main lever 28 is provided below the lever 25 andincludes side walls 28a of sufficient Width to eclipse the left endportions of walls 26a of lever 26 which portions and side walls areconnected by pin 29. It will be noted that Walls 28a are cut awaybeneath the pin Il l sufficiently to clear the latter as the lever 28moves vertically. l

The narrowed end of main lever 28 terminates in a vertical lip Z817 forengaging the adjustable temperature cam 3i) mounted on shaft 3l andmovable by means of the calibrated knob 32. A centrally depressedportion of main lever 28 is apertured to receive the ball 33 whichprojects slightly through the former into contact with block Q where itis maintained by follow-up spring 34 fixed to lever 28 at 35. Properrelative positioning of the levers and switch arms is aided by a coilspring 36 centered on a projection on lever 26 and a similar provisionon follow-up spring 34; coil spring 31 between lever block I9 and theshort arm of lever 26 insures proper contact pressure between contacts24 and bar 25.

Flexible connectors 38 unite switch arms 23 to pin connectors 39 whichextend through the insulated housing closure block Ia; the latterconnectors are electrically connected to spaced conductor strips 4Uhaving lug screws 4I for connection in the electric power circuit to therange heater coil.

The operation of this form of my invention is as follows: With thecomponent parts in the relation shiwn in Fig. l wherein diaphragm I3 isfilled with fluid in the minimum throw position of the cam I5, feelermember I I is rllle'd with fluid at a relatively low temperature, atleast lower than the lowest possible setting of the range cam 30,conduit Ill and its branches are filled; diaphragm 5 hence is in itscollapsed position virtually empty of fluid; lip 28h of lever 28 is inengagement with the low temperature portion of cam 30, and with thecontacts 24, 25 in engagement, the stop screw 2D is engaged by a screwdriver through an aperture (not shown) in housing I and is retractedjust sufficiently to insure that said contacts remain closed as the camI5 rotates 180 degrees to its high position. As the latter action takesplace, the fluid in diaphragm I3 will be forced into diaphragm 5expanding the latter and thereby raising the left end of lever 28 aboutthe low temperature point of cam 30 as a fulcrum. Since the stop screw20 in its adjusted position is ineffective to separate switch arms 23and lever 26, these parts will oscillate as a unit about the pivot pinI1. Thus, the electrical circuit tc the range is maintained as long asthe fluid transfer to the diaphragm 5 originates only in the diaphragmI3. However, as soon as the feeler member II heats up due to receivingheat from the heated pan, for example, the expansion of the fluidtherein is superposed on that from the diaphragm I3 so that theclockwise arcuate movement of the lever 26 about the pin il exceeds thatpermitted the lever 23 by the stop screw 2E] and therefore, the contacts24, 25 are opened. As the cycling duid returns to the diaphragm I3,lever 26 moves in a counterclockwise direction to close the contacts 24,25. It will be observed that rotation of the range cam 3i) to its hightemperature position will raise the fulcrum for the main lever 28 sothat for the adjustment of stop screw 20 previously described a highertemperature of feeler member II and hence greater expansion of itscontained fluid will be required to expand diaphragm 5 suiliciently toseparate the contacts 24, 25 and open the circuit to the heater.

Stop screw 20 is adjusted at the factory as follows: With the powersource disconnected from terminals 4I, the low temperature portion ofcam 30 engaging lip 28h and the cam I5 stopped in its maximum diaphragmcompressing position, the feeler member I I is heated to a temperatureslightly below the lowest temperature setting of the temperatureadjustment knob r32 and the :screw 20 adjusted until the contacts 24, 25are just opening.

The arrangement of the fluid-filled components of the cycling system ofFig. 1 permits the location of the switch and its control knob 32 in theusual control panel position on the range with the da phragm I3, cam I5and its driving motor located at any convenient and relatively coolplace in the range enclosure such as near the base thereof. In theembodiment of Fig. l, furthermore, several diaphragms such as I3corresponding to the number of burners of the range may be spaced aboutthe cam shaft I6 for compression by the same cam I5.

The arrangement of Fig. l may be modified by employing in lieu of thesingle chambered dia phragm 5 specifically shown in this figure, adiaphragm having a rigid dividing wall between the similarly shapedupper and lower walls thereby dividing the diaphragm interior into upperand lower separated chambers. Such a, diaphragm is shown in myco-pending application Serial No. 600,862 led June 22, 1945, andentitled: Corrugated Diaphragms now Patent No. 2,487,947. By connectingthe branch Illb from the diaphragm I3 into the upper nipple blockleading into the upper chamber and connecting the branch IIIa from thefeeler member I I to the conduit ID as in Fig. 1 and thence to the lowerchamber, a thermally inert fluid might be used as the periodicallycirculated medium with the consequent advane tages of ambient stability.Also asingle large diaphragm I3 would suffice for several heater plates.

- It will be apparent that various forms Vof feeler member II may beemployed in the systemof Fig. 1 subject only to the limitation that .thelic;-

uid"withirr the conduit Illa` be forced to the left orright dependent onthe temperature of the feeler member. Thus, the latter may constitutewith conduit Ia a continuous chamber filled with thermo-expansiveliquid. Alternatively, element III may be filled with such a fluid andthe conduit- Illa filled with an ambiently stable, incompressibleliquid, the two fluids being separated by' a flexible wall within theelement I I as shown in my copending application, Serial No. 599,383filed June 14, 1945, and entitled Thermal Responsive'Device and MountingTherefor, now Patent No.- 2,487,946.

Figs. 3, 6 and '7 show a variation of the sys-l tem-of Fig. 1 whereinthe cyclic expansion of diaphragm is effected not bythe circulation of4fluid due to the action of a rotated cam upon a fluid-connecteddiaphragm, but by the periodic heating and cooling of a fixed volume offluid contained within the heater and the diaphragm. In these figuresthe feeler member II has fluid pressure connection to diaphragm 5through conduit Illa and hence exerts lifting force on block `9 as thetemperature of the former is raised. vBetween block 9 and the main lever22 is provided an `'electrically operated, self-contained cycling unitwhich includes an elongated supporting lever 42 having a reversely bentportion provided with an electrical contact 43. The opposite end oflever 42 is provided with a block, 44 of -insulating material securedthereto by screws 45 which may extend also through an in sulating andreenforcing plate 46 as shown in Figure 3. Block 44 is laterallyapertured to receive'a hinge pin 41 which also extends through similarapertures in a pair of parallels ears 48 closely tting the ends of saidblock. Ears 43 arefpreferably formed as welded projections of the mainlever 28 and serve as a laterally stable mounting for the hinge pin 41and the confined block 44. Screws 49 extending into the block 44 fromabove secure an electrical connector plate 53 andan elongated strip ofspring metal 5I thereto. Spring strip 5I serves as a support for an-elongated switch arm 52 to which it is riveted at' 53 and permits saidarm and its contact 52a to be moved downwardly upon the upward movementof the right end of a loop spring 54, the left end Aof `which isapertured to receive a hook projecting from one end of a slot 55 formed'in switch karin 52. As shown'the apertured right end'of vspring 54receives the hooked end of a projection 56. carried-by main lever 28 butinsulated- -therefrom'by suitable strips 5l. Centrally'of the lever 42is mounted by means of a nut 59 a stud 58 to the lower end of which isxed a button 6U of suitable rigid insulating material which "is arrangedto continuously engage block 9 during the operation of the switch.Resting on a sheet of electrical and thermal insulating `material 6I isa coil of thin-walled tubing made of electrical resistance materialhaving one end lsealed as at 62 and the other end connecting with asuitable central bore in the stud 58. The lower Vwall of a diaphragm 5cis suitably fixed to the top of stud 58 and is apertured inline with`said bore to enable expansion fluid from the latter to enter and expandthe diaphragm following connection of leads 59a and 62a to a source ofelectrical current and a closed condition of'contacts 43v and 52a. Thepath of the electric current through the contacts 43, 52a isseen to bethrough the upper lead to electrical connector plate 50, metal strip 5I,switch arm 52, contacts 52a,43, lever 42, nut 58, stud 58, the

6 coiled tubing 62 to lead 62a. heater assembly of Figs. 3, 6 and 7 isnot claimed herein, in as much as it is fully described and claimed inmy copending application Serial No. 600,862 supra.

The upper wall of diaphragm 5c has centrally secured thereto the taperedstud 53a adapte-:l to continuously engage a contact ball 63 such as avitreous bead, held in a suitably tapered apela ture in the main lever28 by spring 34. Adjust-' ment screw 64 threaded in a block 65 ofinsulat ing material secured to the lever 42 serves as lower stop forthe spring mounted lever 52 as it snaps to its lower position andprovides means for varying the ori-off cycle.

The operation of this embodiment of my invention will, it is thought, beapparent from the foregoing. The diaphragm 5c with its associatedheater, lever and. switch elements provides the same cycling deflectionsfor lever 28 as is provided by the driven cam I5 and diaphragm I3 ofFig. 1; adjustment of this form of my inven-` tion is carried out in thesame way as in the arrangement shown in Figs. l and 2. Now visualiz.-

ing the complete switch of Fig. 3 as constituting the switch componentsof Fig. l modified by sube' stituting the Fig. 3 structure for the lever28 and all parts therebelow, shown also in Figs. 6`and7, it will beapparent that the periodic heating and cooling of diaphragm 5c and itsconsequent ex pansion and contraction will raise and lower the left endof lever 28 with a periodicity dependent on the heat capacity of thediaphragm and the adjustment of screw 64. This will be evident since theright end of lever 42 is hinged to lever 28 and the distance between theball 63 and the button 60 increases as the diaphragm 5c expands due toheat produced by the electric current flow-` ing through the tube 62. Asthe left end of lever 28 is moved upwardly, projection 56 is carriedupwardly also to such a point that the loop spring 54 snaps the switcharm 52 downwardly against the stop 64 thus opening the electricalcontacts 43, 52a and allowing the diaphragm to cool and contract and theleft end of lever 28 to fall and thus approach the lever 42. cooling hasbrought levers 28 and 42 together suiciently to enable the projection 56to swing the spring 54 to contact closing position, the electric circuitto the tube 62 will again be closed and the cycle will continueindefinitely.

It will be observed that the action of the heat..-` ed diaphragmcorresponds to that of diaphragms 5 and I3 and the cam I5 of Fig. l. Thefluid pressure transmitted by the feeler element II due to heatingexpands diaphragm 5 (Fig. 3*) and therefore acts to raise the left endof lever 28 and separate contacts 24-.25 controlling the energization ofthe range heater element until such contacts are closed for only such afraction of the operative cycle of the diaphragm 5c,.heater 62 unit aswill supply a quantity of heat equal to that dissipated by the cookingvessel, i. e., a stable heat transfer condition. In addition to theelimination of the motor and its .cycling cam I5, the diaphragm I3 andnecessary tubing, the Figs. 3, 6 and 7 embodiment is quite compact andis cheaper to manufacture than the first-described form of my invention.

In Figs. 4 and 5 there is shown an extremely compact switch which may bemost advantageousf.

The diaphragme.-

When diaphragm' of an adjustable 'stop for varying the relation of themain lever and the range cam. In Figs. 4 and 5 a housing 66 closed by atop wall 61 and end wall 68 of insulating material is secured to therange panel 69 by suitable means such as screws 10. The left end of thehousing 66 is provided with an elongated block 1I of insulating materialwhich is held in place by one or more recessed screws 12, and carries onits vertical face a spaced pair of riveted or otherwise connected springstrips 13. A laterally extending, elongated block 14 of insulatingmaterial serves to bridge by means of the connecting means 15, the upperends of the spring strips 13 and carries on its upper surface a pair ofspaced contact arms 16, 11 bearing contacts 18, 19 respectively at theouter ends thereof. A spring contact arm in the form of a flat strip 80has one end fixed to the top middle portion of the block 1I by meanssuch as screw 6I and extends beneath the block 14 to which it isanchored as by a rivet 82 extending through the strip and block andterminating in a head 83 in a recess provided in the latter. A coilspring 84 disposed between the top wall 61 and the block 14 serves toflex the spring strip 80 downwardly against the vertex of a generallytriangular level` 85 the opposite ends 86 of which are snapped oversuitable hinge-forming projections 81 extending from the side walls ofthe housing 66. formed centrally of the lever 85 is adapted to transmitthe pressure of spring 84 to the block 93 of diaphragm 5.

The right end of spring strip 80 carries in suitable insulatingrelationship a bridge member 89 secured thereto at 89a and havingcontacts 9| adapted to engage contacts 18, 19, respectively as shown inFig. 4. Strip 80 is reenforced by a stiff strip 92 riveted thereto at89a and 93 and having a downwardly offset cani-engaging end which isadapted to be bent upwardly against an `adjustable abutment such as thecamV 94 of the range knob 95 by means of the screw 96 threaded throughbracket 91 welded to the offset end. Leads 90 connect the ends of switcharms16, 11 with terminal strips 99 as will be apparent from Figures 4and 5.

Zero adjustment of the switch of Figs. 4 and 5 isI easily made followingthe procedure already described, the coarse adjustment being effectedthrough positioning of the cam 94 prior to tightening of its retainingscrew, followed by necessary movement of screw 9S which is accessiblefrom the switch exterior by means of a suitable opening (not shown) inthe housing 66. In operation the cycling travel of the block 98 ofdiaphragm 5 is such that separation of contacts 18, 19 and 9| does notresult from engagement of the right end of strip 92 with the cam S4,strip 80 merely flexing and the arms 16, 11 moving with it. When thefeeler member pressure is superimposed on the cycling pressure,however', the movement of blocl; 98 is sufficient to flex strip 8E tosuch an extent that the block 14 is movedA upwardly and to the left andthe arms 'I6 and 11 are moved away from the strip 89 and strip 92 withconsequent opening of the contacts.

The spring-hinged modification of Figs. 4 and 5 provides in compact formthe same operating advantages of the Figs. 1 and 2 construction and inaddition eliminates the friction, lost motion and misalignment of partsinherent in greater or lessI degree in all pivoted lever systems.

While I have shown and described certain preferred embodiments of myinvention, it will be.

A projection 88 8 understood that I do not intend to be limited thereto,but only as may be within the scope of the following claims.

I claim:

l. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow membercoupled to said means to constitute a continuous enclosure, athermo-expansive fluid filling said enclosure, fiuid circulating meansalso connected to said chamber means for cyclicly forcing liquidthereinto and withdrawing the same therefrom, and a switch having a pairof contactcarrying arms which are relatively movable to open and closethe contacts thereof and one of which arms is disposed inpressure-receiving relation withsaid expansible chamber means andthereby movable with respect to the other of said arms whereby therelative positions of said contacts at any selected instant during thecyclic expansion of said expansible chamber is dependent on thetemperature of said temperature-responsive member.

2. The combination set forth in claim l in which there is furtherprovided cam means also disposed in pressure-receiving relation withsaid expansible chamber means and in pressuretransmitting relation withone of said arms for modifying the effect of said last means upon saidlast named arm.

3. The combination set forth in claim l in which the fluid displacementcharacteristics of said fluid circulating means are so chosen withreference to those-of said member and also the volumetric capacity ofsaid diaphragm means that said contacts remain in one of said positionsduring the cyclic operation of said fluid circulating means alone butmove to the other of said positions upon the further expansion of saiddiaphragm means by heating and resultant expansion of said member.

4. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow membercoupled to said means to constitute therewith a continuous enclosure, athermo-expansive fluid filling said enclosure, cyclicly operated fluidcirculating means located remote from said first means and fluid coupledthereto for forcing liquid thereinto land withdrawing the sametherefrom, and a switch having a pair of contact-carrying arms wihichare mounted for relative movement to effect an open and a closedposition, respectively, of said contacts and also movable in unisonduring a closed position interval of said contacts and one of which armsis disposed in pressurereceiving relation with said expansible chambermeans and thereby movable with respect to the other of said arms, thefluid displacement characteristics of said fluid circulating means beingso chosen with reference to those of said member and the volumetriccapacity of said first means that said contacts remain closed during theoperation of said fluid circulating means alone, but move to an openposition upon the further expansion of said first means by heating andconsequent expansion of said member.

5. The combination set forth in claim 4 in which there is furtherprovided an adjustable abutment also disposed in pressure-receivingrelation with said expansible chamber means and in pressure-transmittingrelation with one of said arms for modifying the effect of said chambermeans upon said one arm.

6. A fluid-pressure cycling system for electric -plurality of pivoted,arms spring-biased to closed-contact position j and a lever carried byone of said switch arms .1heaterscomprising expansible chamber means, a

temperature-responsive, hollow member coupled to Asaid means toconstitute a continuous enclothereinto and withdrawing the sametherefrom, a contact-carrying switch and disposed between the latter andsaid chamber means and adapted to transmit the pressure of the latter tosaid arms to move said arms synchronously` with the operation of saidfluid circulating means and to effect opening and clos- Hing of saidcontacts in response to the temperature'of said member.

uw. A uid pressure cycling System for electric heaters comprisingexpansible chamberl means, a temperature-responsive, hollow membercoupled to saidmeans to constitute a continuous enclosure, athermo-expansive uid filling said enclosure, uid circulating means alsoconnected to said chamber means for cyclicly forcing liquid Athereintoand withdrawing the sameA therefrom,

a A.plurality of pivoted, contact-carrying switch arms spring-biased toclosed-contact position and a lever carried by one of said switch armsand disposed between the latter and said chamber means and adapted totransmit the pressure of the latter to said arms to move said armssynchronously with the operation of said fluid circulating` means and toeiect opening and closing of said contacts in response to thetemperature of said member and an adjustable cam adapted to engage oneend of said lever to vary `the temperature effect of said member uponthe l opening and closing of said contacts.

disposed for relative, contact-opening movement and also unitary,closed-contact movement,

means for effecting said movements including a pressure-transmittingmember disposed between said rst means and said arms, and a stationaryabutment having an adjustable, intercepting positio'n with respect tosaid last means and'said arms, whereby the duration of the open-contactcondition of said arms will be dependent on the temperature of saidmember and the position of said abutment.

9. A fluid-pressure cycling system for electric Vvheaters comprising acasing, expansible chamg -ber means mounted therein, atemperature-responsive hollow member outside said casing and `formingwith said chamber a fluid-tight enclosure, a thermo-expansive fluidfilling the latter, .an adjustable cam and a plurality of contact-car--rying switch arms mounted in pressure-transmitting relation therewithwithin said casing and disposed in pressure-receiving relation with saidchamber' means, and a cyclicly operated, corrugated diaphragm disposedto exert cyclicly ad- -ditive pressure on said cam and contact-carryingswitch arms whereby the contacts of the latter will be cyclicly openedand closed in response to the total pressures exerted by said fluid andsaid diaphragm.

l0. A duid-pressure cycling system for electric heaters compriing acasing, a corrugated .diaphragm mounted therein, atemperature-responsive, hollow member outside said casing and formingwith said diaphragm va fluid-tightenclosure, a thermo-expansive fluidlling the latter, an adjustable cam and a pluralityv of contact-carryingswitch arms mounted in pressuretransmitting relation in said casing, alever having one end fulcrumed on said cam and the other end pivotallyconnected to one of said arms and in pressure-transmitting relation withsaid diaphragm and adapted to transmit the pressure of the latter tosaid cam and arm and a cyclicly operated diaphragm fluid-coupled to saidenclosure to exert additive pressure on said first-mentioned diaphragmwhereby the contacts of said switch arms will be cyclicly opened andclosed in response to the total pressure transmitted by said fluid.

11. A fluid-pressure cycling system for'electric heaters comprising acasing, expansible chamber means mounted therein, atemperature-responsive, hollow member outside said casing and formingwith said chamber a fluid-tight enclosure, a thermo-expansive fluidfilling the latter, an adjustable cam and a plurality` ofcontactcarrying switch arms mounted in said casing, a lever having oneend fulcrumed on said cam and the other end pivotally connected to oneof said arms and disposed in pressure-transmitting relation with saidchamber means and adapted to transmit the pressure of the latter tosaidcam and arm, an expansible chamber lled with Aa thermo-expansivefluid and disposed between said first chamber and said lever, andcyclicly energized, electrical heating means for said last chamberwhereby the additive pressures of said chambers will be transmitted tosaid switch arms to cyclicly open and close the contacts thereof- 12. Ahuid-pressure cycling system for electric heaters comprising a casing,expansible chamber means mounted therein, a temperature-responsive,hollow member outside said casing and forming with said chamber afluid-tight enclosure, a thermo-expansive fluid lling the latter, anadjustable cam and a plurality of contact-carrying switch arms mountedin said casing', a lever having one end fulcrumed on said cam and theother end pivotally connected to one of said arms and disposed inpressure-transmitting relation to said chamber means and adapted totransmit the pressure of the latter to said cam and arm, an expansiblechamber filled with a thermoexpansive fluid and disposed between saidrstchamber and said lever, a tubular heater of electrical resistancematerial located beneath said chamber and forming a continuous enclosuretherewith, a thermo-expansive fluid llingsaid enclosure and anelectrical circuit for said heater which is cyclicly energized therebyfor producing a cycling pressure in said last chamber which is added tothat of the first chamber -tov cyclicly open and close the contactscarried by said switch arms.

13. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow member.coupled to said means to constitute a continuous enclosure, athermo-expansive fluid filling said enclosure, fluid circulating meansalso connected to said chamber means fOr cyclicly forcing fluidthereinto and withdrawing the same therefrom, a plurality ofcontact-carrying switch arms arf ranged to be moved in unison tomaintain the l l closed condition of said contacts in response to thecyclic expansion of said chamber means by said circulating means orrelatively to each other to open said contacts when said chamber meansfurther expands due to the attainment of an elevated temperature in saidhollow member and an adjustable abutment disposed in the path ofmovement of one of said arms for blocking the movement of the latter toestablish an opencontact position from which the remaining arms f aremoved upon the further expansion of said chamber.

14. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a

temperature-responsive, hollow member coupled to said means toconstitute a continuous enclosure, a thermo-expansive fluid filling saidenclosure, fluid circulating means also connected to said chamber meansfor cyclicly forcing iluid thereinto and withdrawing the same therefrom,e

a plurality of contact-carrying switch arms arranged to be moved inunison to maintain the closed condition of said contacts in response tothe cyclic expansion of said chamber means by said circulating means orrelatively to each other l to open said contacts when said chamber meansfurther expands due to the attainment of an elevated temperature in saidhollow member, an adjustable abutment disposed in the path of movementof one of said arms for blocking the latter to establish an open-contactposition from which the remaining arms are moved upon the furtherexpansion of said chamber means, and adjustable means carried by saidone arm for deforming the latter to vary its interval of blocking bysaid abutment.

15. A fluid-pressure cycling system for electric heaters comprisingeXpansible chamber means, a temperature-responsive hollow member coupledto said means to constitute a continuous enclosure, a thermo-expansivefluid. filling said enclosure, fluid circulating means also connected tosaid chamber means for cyclicly forcing fluid thereinto and withdrawingthe same therefrom, a support bearing a plurality of normally disposedspring strips, a second support carried by said strips, a plurality ofcontact-carrying switch arms disposed on either side of said secondsupport and arranged to be moved in unison to maintain the closedcondition of said contacts or relatively to each other to open saidcontacts and an adjustable abutment disposed in the path of movement ofone of said arms for blocking the latter to thereby open said contactsupon the attainment of an elevated temperature in said hollow member.

16. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow membercoupled to said means to constitute a continuous enclosure, athermo-expansive fluid filling said enclosure, fluid circulating meansalso connected to said chamber means for cyclicly forcing fluidthereinto and withdrawing the same therefrom, a support bearing aplurality of normally disposed spring strips, a second support carriedby said strips, a plurality of contact-- carrying switch arms disposedon either side of said second support and arranged to be moved in unisonto maintain the closed condition of said contacts or relatively to eachother to open said contacts, an adjustable abutment disposed in the pathof movement of one of said arms for blocking the latter to thereby opensaid contacts upon the attainment of an elevated temperature i2 in saidhollow member, and adjustable means carried by said arm for deformingthe latter to vary its interval of blocking by said abutment.

17. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow memberforming with said chamber a fluid-tight enclosure, a thermo-expansivefluid lling the latter, a support having a plurality of normallydisposed spring strips, a second support carried by said strips, aplurality of contact-carrying switch arms disposed on either side ofsaid second support and arranged to be moved in unison to maintain theclosed condition of said contacts or relatively to each other to opensaid contacts and an adjustable abutment disposed in the path ofmovement of one of said arms for blocking the latter to thereby opensaid contacts upon the attainment of an elevated temperature in saidhollow member.

18. A duid-pressure cycling system for electric heaters comprisingexpansible diaphragm means, a temperature-responsive, hollow membercoupled to said means to constitute a continuous enclosure, athermo-expansive fluid filling said enclosure for transmitting pressureto said means upon heating of said member, uid circulating means alsoconnected to said diaphragm means for cyclicly forcing fluid thereintoand withdrawing the same therefrom.. a switch including a plurality ofrelatively movable, contact-carrying arms having a closed contactposition and an open contact position, spring means disposed to urgesaid arms into one of said positions and means disposed between saiddiaphragm means and said arms for transmitting pressure from the formerto the latter for moving said switch arms into the other of saidpositions in response to heating of said member.

19. A duid-pressure cycling system for electric heaters comprisingexpansible diaphragm means, a temperature-responsive, hollow membercoupled to said means to constitute a continuous enclosure, athermo-expansive uid filling said enclosure for transmitting pressure tosaid means upon heating of said member, fluid circulating means alsoconnected to said diaphragm means for cyclicly forcing fluid thereintoand withdrawing the same therefrom, and a switch including a pluralityof relatively movable, contact-carrying arms having a closed contactposition and an open contact position, spring means disposed to urgesaid arms into closed Contact position and means disposed between saidirst means and said arms for transmitting pressure from the :former tothe latter for moving said arms to open contact position in response toheating oi said member.

20. A fluid-pressure cycling system for electric heaters comprisingexpansible chamber means, a temperature-responsive, hollow membercoupled to said means to constitute a continuous enclosure, athermo-expansive fluid filling said enclosure, fluid-circulating meansalso connected to said chamber means for cyclicly forcing liquidthereinto and withdrawing the same therefrom, a plurality of pivoted,contactcarrying switch arms spring-biased to closed contact position,and a lever disposed between one of said arms and said chamber means andadapted to transmit the pressure of the latter to said arms to move saidarms Asynchronously with the operation of said fluid-circulating meansand to eiect opening and closing of said 13 contacts in response to thetemperature of said member.

21. A fluid-pressure operated, adjustable switch comprising a housing,an expansible chamber having a conduit adapted to be connected to anexternal source of fluid pressure, an adjustable abutment carried bysaid housing and spaced from said chamber, an elongated,contact-carrying switch arm having one end resiliently mounted withrespect to said housing and remote from said abutment and having anopposite end portion adapted to be intercepted by the latter, saidportion being adjustably deformable toward and away from said abutmentand independently thereof, said arm having also an intermediate portiondisposed in pressure receiving relation with said chamber, and a secondcontact-carrying switch arm resiliently mounted with respect to saidhousing and movable from a closed-contact position with said first armto an open contact position away from the latter as said chamber expandsand said rst arm moves to its abutment-intercepted position.

JURG A. SENN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,975,851 Kimball Oct. 9, 19341,976,843 Eskin Oct. 16, 1934 1,981,282 Smith Nov. 20, 1934 2,006,178Piron June 25, 1935 2,091,734 Himes Aug. 31, 1937 2,150,674 Dudgeon Mar.14, 1939 2,224,552 Sickinger Dec. 10, 1940 2,256,840 Haines Sept. 23,1941 2,273,734 Pearce Feb. 17, 1944 OTHER REFERENCES Journal of theAmerican Chemical Society, vol. 42, Jan. 1920, pages 60-68.

